hmcdrvfs - Mount a FUSE file system for remote access to media in the HMC media drive

Ubuntu 22.04 LTS LPAR mode z/VM guest

Use the hmcdrvfs command for read-only access to contents in a DVD, CD, or USB-attached storage in the media drive of an HMC.

Before you begin:

The fuse.hmcdrvfs file system needs access to device node /dev/hmcdrv. This node is created automatically when the hmcdrv kernel module is loaded.
On the HMC, the media must be assigned to the associated system image (use menu Access Removable Media).
In a z/VM® environment, the z/VM guest virtual machine must have at least privilege class B. The media must be assigned to the LPAR where the z/VM hypervisor runs.
For Linux in LPAR mode, the LPAR activation profile must allow issuing SCLP requests.

With the media assigned to your Linux instance, this command creates a fuse.hmcdrvfs file system with the media content at the specified mount point.

To unmount file systems that you mounted with hmcdrvfs, you can use umount.

hmcdrvfs syntax

Where:

-o or --opt

FUSE or mount command options; for the FUSE options see the following lists, for mount options see the mount man page.

<fuse.hmcdrvfs-options>

options specific to the fuse.hmcdrvfs file system:

-o hmclang=<language>: specifies the language setting on the HMC; for valid values, see the locale man page.
-o hmctz=<time zone>: specifies the time zone setting on the HMC; for valid values, see the tzset man page.

<mount-options>

options as available for the mount command. See the mount man page for details.

<fuse-options>

options for FUSE. The following options are supported by the cmsfs-fuse command. To use an option, it must also be supported by the version of FUSE that you have.

-d or -o debug: enables debug output (implies -f).
-f: runs the command as a foreground operation.
-s: disables multi-threaded operation.
-o allow_other: allows access to the file system by other users.
-o allow_root: allows access to the file system by root.
-o default_permissions: enables permission checking by the kernel.
-o fsname=<name>: sets the file system name.
-o subtype=<type>: sets the file system type.
-o max_read=<n>: sets maximum size of read requests.
-o direct_io: uses direct I/O.
-o kernel_cache: caches files in the kernel.
-o [no]auto_cache: enables or disables caching based on modification times.
-o umask=<mask>: sets file permissions (octal).
-o uid=<n>: sets the file owner.
-o gid=<n>: sets the file group.
-o entry_timeout=<secs>: sets the cache timeout for names. The default is 1.0 second.
-o attr_timeout=<secs>: sets the cache timeout for attributes. The default is 1.0 second.
-o ac_attr_timeout=<secs>: sets the auto cache timeout for attributes. The default is the attr_timeout value.
-o max_readahead=<n>: sets the maximum read ahead value.
-o async_read: performs reads asynchronously (default).
-o sync_read: performs reads synchronously.
-o no_remote_lock: disables remote file locking.
-o intr: allows requests to be interrupted
-o intr_signal=<num>: specifies the signal to send on interrupt.

-v or --version

displays version information for the command.

-h or --help

displays a short help text, then exits. To view the man page, enter man hmcdrvfs.

The following options for mount policy can be set in the file /etc/ fuse.conf file:

mount_max=<number>: sets the maximum number of FUSE mounts allowed for non-root users. The default is 1000.
user_allow_other: allows non-root users to specify the allow_other or allow_root mount options.

Examples

To mount the contents of the HMC media drive at /mnt/hmc without any special options, use:
```
# hmcdrvfs /mnt/hmc 
```
If the hmcdrv kernel module is not loaded, load it before you issue the hmcdrvfs command:
```
# modprobe hmcdrv
# hmcdrvfs /mnt/hmc 
```
To translate the UID and GID of files on the HMC media drive to your system users and groups along with overriding the permissions, issue, for example:
```
# hmcdrvfs /mnt/hmc -o uid=500 -o gid=1000 -o umask=0337
```
To speed up transfer rates to frequently accessed directories, use the cache timeout option:
```
# hmcdrvfs /mnt/hmc -o entry_timeout=60
```
If the HMC is in a different timezone and is configured for a different language use, for example:
```
# hmcdrvfs /mnt/hmc -o hmclang=de_DE -o hmctz=Europe/Berlin
```
To also disregard any Daylight Saving Time, specifying hours west of the Prime Meridian (Coordinated Universal Time):
```
# hmcdrvfs /mnt/hmc -o hmclang=de_DE -o hmctz="GMT-1"
```
To unmount the HMC media drive contents mounted on /mnt/hmc, issue:
```
# umount -u /mnt/hmc
```